Ominous News For AIDS Victims

More than three-quarters of all U.S. patients with the AIDS virus have an infection that resists one or more of the drugs used to treat it, researchers reported on Tuesday.

They said the grim news meant that drug-resistant HIV had spread even faster than was feared, and the lifesaving cocktails of drugs that help many patients lead normal lives were becoming increasingly limited in their usefulness.

Unless better drugs are developed soon, or until a vaccine is invented that can control the virus, patients will have ever-lessening chances of using drugs to counter AIDS, the researchers told a conference sponsored by the American Society of Microbiology.

Some already have no chance at all, Dr. Douglas Richman of the Veteran's Administration hospital and the University of California in San Diego, who led the study, said.

"The percentage of drug resistance that we've seen in the study exceeded what any of the investigators expected," said Richman.

It's no surprise to Dr. Anthony Fauci of the National Institutes of Health, reports CBS News Medical Correspondent Elizabeth Kaledin. He says the virus is mutating to outsmart the drugs and the pressure is on to find better treatments.

"It's imperative for us to continue to try to develop new drugs, better drugs."

Richman and colleagues tested blood samples taken in 1999 from 1,647 men and women. They used a test made by South San Francisco-based ViroLogic Inc. to test how the virus responded to the many available drugs used to test HIV.

"They reflect almost 209,000 people and about 130,000 who have detectable viremia (levels of virus in the blood)," Richman said.

Of these, Richman's team told the Interscience Conference on Antimicrobial Agents and Chemotherapy in Chicago, 78 percent carried virus that resisted at least one drug. "Just over 50 percent of them were resistant to more than one class of drugs," Richman said.

Other studies had shown that HIV was evolving to evade nearly every drug available, but these are the most startling numbers yet.

"Many of the previous studies were relatively small and in highly selected populations, so that accurate estimates were not possible," Dr. Samuel Bozette, who worked on the study, said in a statement.

Bacteria are known to mutate to resist drugs, which is why new antibiotics are being developed regularly.

But Richman said a virus such as HIV is trickier than any bacteria. "The reason is this virus replicates to higher levels at faster rates, so it evolves faster," he said.

"Once resistance is there, it stays in a patient for the rest of his or her life. You don't get cured of an HIV species."

Among the study's findings: